Methods of this kind for operating a pressing unit are known. For example, reference may be made to WO 99/19947. The pressing unit known from this document is hydraulically driven. In addition, pressing units of this kind that are driven directly by an electric motor are also known. In this respect, reference may be made, for example, to DE 203 05 473 U1. Instead of two pressing jaws, it is also possible to provide just one pressing jaw, which is to be moved against a fixed counter-stop. See, for instance, U.S. Pat. No. 5,727,417.
It has also already been proposed, see for instance German patent application 10 2006 026 552, which is not a prior publication, that, when the pressing jaws are released in such a way that they can move or can be moved back into the opened or openable starting position (with regard to ‘can be moved’ it should be pointed out that, although pressing jaws of this kind are basically openable, they could also be biased by a spring into a closed position, see for instance DE 10 2005028 083 A1), an interruption of the movement into the starting position may be performed in such a way that a next pressing operation can be commenced right away from an intermediate position thereby chosen. Therefore, time is saved if a complete movement into the starting position is not required. This interruption must take place in each case in response to specific actuation.
Furthermore, measures intended to make it possible to check whether pressing has actually been carried out have already been proposed in various respects. EP 1 092 487 A2 has proposed in this respect a device on the pressing jaws which allows them to be reopened only after they have been completely pressed together. However, this measure for checking complete pressing is relatively complicated.